There was a problem with the configuration in the SpringSurf config for sample apps. A bean to handle multi-part form data was incorrectly being applied - which was attempting to read the request before the proxy had a chance to deal with it:
this bean has now been removed from the samples!! It is working fine in RC1/RC2
<bean class="org.springframework.web.multipart.commons.CommonsMultipartResolver" id="multipartResolver">
<property name="maxUploadSize" value="10000000"/>
from my tests.